periscope -
A form of viewing device that allows the viewer to see things at a different height level and usually with minimal visibility.
periscope -
A general or comprehensive view.
Verb
periscope -
To rise and peer around, in the manner of a periscope.
Wikipedia
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I.
